A generic module is described, for example, in German Patent Application No. DE 10 2007 031 562 A1. Modules of this type are used in particular as sensor modules, for example for peripheral acceleration sensors in motor vehicles.
In the conventional sensor modules, the EMC protection of the electronic components is achieved via a shielding between two ground planes. The lower ground plane is formed, for example, by the GND layer on a printed circuit board or without a printed circuit board, by a flat part of a terminal pin of the module, while the upper ground plane is formed by the pressed screen of the sensor IC (inverted lead frame).
In future airbag sensors the electronic system should be contacted in a separate manufacturing station using metallic insert parts (lead frame), which, at the same time, form the plug-in contacts of the module. The assembly: electronics plus insert parts should be enclosed using an elastomer shell and then extrusion-coated using a thermoplast. The outer housing of the module is manufactured by extrusion-coating using a first and a second component in a special two-component injection molding tool to ensure a continuous manufacturing process. However, in this “2C direct extrusion-coating” process, a ground shielding of the conventional type, i.e., using large ground planes, cannot be implemented, since only narrow metallic insert parts are processable in the injection molding tool, so that sensitivity to EMC interference would be higher. Furthermore, metal coating of all sides of the housed sensor chip (EMC coating) is not suitable for automotive applications according to the current state of the art because it results in a short-circuit between the plug pins.